Radiographic inspection method



' Dec. 3, 194e.

R. Gl. RHOADES 2,412,174 RADIOGRAPHIC INSPECTION METHO Filed June24,1946

FIIE E Patented Dec. 3,1946

RADIOGRAPHIC INSPECTION METHOD Russell G. Rhoades, San Francisco,Calif., as-

signor to Bechtel Brothers McCone Company, a corporation of DelawareApplication June 24, 1946, Serial No. 678,783

(Cl. Z50-65) 2 Claims.

The present invention relates to the radiographic examination of weldsand more particularly to an improved method and apparatus forradiographing circumferential welds in pipe lines and the like.

The radiographic examination of welds in pipe lines presents problemsnot encountered in the radiographing of welds in pressure Vessels suchas boilers which are provided with openings through which either aradiation emanating means or a lm carrier' may be introduced into theinterior of the vessel. Pipe lines are laid in lengths of many miles andare devoid of any such (,)peiiiiigs and this has made it necessary totake advantage of theV open end in order to obtain the necessary accessto the interior thereof for radiographic weld inspection.

Where radiographic inspection of pipe line welds is effected byintroducing through an open end of the line either a film carrier or aradiation emanating means in the form of X-ray apparatus or a capsule ofradioactive material, an I interruption of construction work on the pipeline is necessary for each inspection. If, on the other hand, both thesource of radiation and the lm are disposed exteriorly of the pipe line,at least two separate exposures are necessary to inspect welds evenwhere the pipe is of small diameter, and methods in which both the filmand source of radiation are outside the pipe line are impracticable forother reasons when the pipe is of large diameter.

The principal object of my invention is to make possible theradiographic examination of pipe line welds by a single exposure withoutrequiring access to an open end of the line.

A further and more specific object of my invention is to provideapparatus facilitating the carrying out of the radiographing method ofmy invention.

The foregoing principal object, together with other objects andadvantages which will appear hereinafter, is accomplished, ln general,by making a relatively small temporary opening in the wall of a pipeline adjacent but spaced from a circumferential weld therein, andutilizing said opening to introduce into the interior of thepipe line asource of radiation; so positioning the latter as to insure a clear pathfor radiation therefrom to the circumferential weld to be radiographedand through said weld to a film held on the exterior of the pipe overthe weld. After the necessary exposurel time has elapsed, the radiationsource is withdrawn and the temporary opening, which is of onlysufficient size to freely admit a holder for the radiation source, ispermanently sealed. l

The method and apparatus by which the foregoing objects are attainedwill be best understood from the following description ofv preferredprocedure and apparatus, reference being had to the accompanyingdrawing, forming a part of this specification, in which:

Figure 1 is a perspective view of a preferred form of apparatusembodying the present invention; the same being illustratedY iny placeon a pipe line; v

Figure 2 is a detail'view of a portion of the apparatus illustrated inFigure l; and

Figure 3 is a detail view illustrating a preferred way of sealing thetemporary opening referred to herein.

In Figure 1 of the accompanying drawing there is illustrated a portionof a conventional pipe line I0 provided with the usual covering II andconstructed in sections yjoined together by circumferential welds suchas that illustrated at I2.

According to the present invention, a radiograph of any circumferentialweld I2 in a pipe line I0, which may extend for many miles, can

be made Without access to an open end of the pipe line. To facilitatethe carrying out of the radiographing method of the present invention,there is preferably pro-vided apparatus of the character illustrated inFigures 1 and 2 which comprises an orienting device l5 adapted to restin stable equilibrium on thev curved upper surface of a cylindricalobject such as a pipe line I0. For this purpose the device I5 ispreferably made in the form of a plate having four legs I6 by means ofwhich the device may be firmly and stably supported on the curvedsurface of a pipe during any period required for a complete radiographexposure.

Secured to the orienting device I5 is a carrier I'B preferably in theform of a tube secured to the orienting device I5 by welding asindicated at I9.

The tube I8 is curved as indicated in Figures 1 and 2 and proportionedso that its lower` end lies outside of the area which the orientingdevice I5 overlies when it is disposed in the operating position inwhich it is shown in Figure 1.

When the apparatus is to be used, there is extended through the tube IBan assembly consisting of a flexible wire 2l the upper end of which issecured to a handle 22 provided with'a hooked portion 23 adapted toengage over the upper end of the tube I8. Attached to the lower end ofthe flexible wire 2I is a spring 24 the lower end of lwhich is in turnconnected to a second flexible wire 25 provided with a hook 26 at itslower end. Removably secured to the lower end of the wire 25 by the hook2B is a conventional radium capsule 21 which is preferably employed asthe radiation emanating means in the practice of the present invention,although equivalent devices such as X-ray emanating means are, ofcourse, well known in the art.A

'I'he length ofthe wire and spring assembly 2 I, 24, 25 is soproportioned to the length of the tube I8 that when the radium pill 21is engaged in the open lower end of the tube I8 as shown, substantialtension must be applied to the spring 24 in order to engage the hook 23-over the open upper end of the tube I8. This spring tension serves tomaintain the radium capsule 21 in position at the lower open end of thetube I8.

In carrying out the method of the present invention utilizing the abovedescribed apparatus, which is known in the art as a jig, a temporaryopening such as that illustrated at 30 in Figure 1 of the accompanyingdrawing is made in the'wall of the pipe line at such a distance from theplane of the weld I2 as will bring the radium capsule 21 into thegeneral plane of the weld i2 when the jig is positioned as illustratedin Figure l with the tube I8 extending through the temporary opening 30.It is also to be noted that the tube I8 is so positioned with respect tothe orienting device I5 that, when the latter isv in the stable positionillustrated, the radium capsule 21 is substantially on the longitudinalaxis of the p-ipe line. With the device thus positioned,V a nlm 32,which is preferably placed in position before the tube I8 is insertedthrough the hole 33 and which overlies all of the weld I2 exteriorly ofthe pipe line II), will be uniformly exposed and will provide aradiograph of uniform density'showing all portions of the weld I2.

After the necessary exposure time, determined in'a manner well known inthe art, has elapsed, the tube I8 is withdrawn from the temporaryopening 30 by lifting the orienting device I5 preferably by such meansas the hooked handle 33 illustrated in Figure l, and the temporaryopening is permanently sealed by means such as a screw plug 44 (Figure3) inserted in the opening 30 and welded in place as illustrated at 45.

What is claimed is:

1. A method of radiographing a circumferential weld in a pipe lineaccess to which from an open end is impracticable, comprising` the stepsof ymaking a temporary opening in the wall of said pipe line at a pointadjacent said weld, introducing radioactive material through saidtemporary opening, positioning said radioactive material in the generalplane of said weld and substantially on the axis of said pipe line,exposing to the emanation of said radioactive material iilm wrappedaround said pipe line exteriorly thereof at said weld, withdrawing saidradioactive material through said temporary opening, and sealing saidtemporary opening.

2. A method of radiographing a circumferential weld in a pipe lineaccess to which from' an open end is impracticable, comprising the'steps of making a temporary opening. in the wall of said pipe line at apoint spaced a predetermined distance from said weld, utilizing a jighaving orienting means engageable withY the exterior wall of said pipeline adjacent `said temporary opening and v radioactive materialpositioning means offset with respect yto said orienting means by theaforesaid predetermined distance and extendible through said opening tointroduce radioactive material through said temporary opening andposition said material in the general plane Vof said weld andsubstantially on the axis of said pipe line, exposing to the emanationVof said radioactive material film wrappedr` around said pipe lineexteriorly thereofatL said weld, withdrawing said radioactive material.through Asaid temporary opening, and sealing said temporary opening.

' u RUSSELL G. RHOADES.

